Portable punching tool



Feb 26, 1957 A. MARcoUx PORTABLE PUNCHING Toor.

Filed May 19, 1953 yur/1111111 4115,

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nited States Patent ce 2,782,855 Patented Feb. 26, .l1-957 PORTABLE PUNCH'ING TOOL Application YVMay 19, 1953, Serial No. l356,011

3 Claims. l(Cl. 164-94) This invention relates to a device for 'piercing holes in light gauge metals, and more particularly to a portable punching tool for piercing holes 'in aircraft components to permit the easy attachment of anchor nuts, nut plates, or the like. l

Heretofore, when it was found necessary t'o install a large quantity of nut plates or the like in 'a given structure, every attempt was made to complete the Iir'istallaition at the bench, where, by the use of old and well known drill-jig methods, the bolt hole and thenut plate rivet holes were drilled, the nut plates were riveted `in position, and then the part was installed .in its parent structure, e. g. an airplane fuselage or wing. If the structural part could not be fabricated at the bench, it was then necessary to install it in the parent structure, individually drill, with a hand-held electric drill, lboth 'the bolt holes and the fnutplate rivet holes, and then set the nut-plate rivets with a conventional rivet gun. This is obviously a vtime consuming, cumbersome, and generally unsatisfactory procedure. The nut plate holes are frequently not located properly with respect to the bolt holes, requiring re-drilling and relocation, if possible, or perhaps rejection of an expensive part, if correction is not possible.

The present invention comprises a vibratory or rattle type pneumatic hammer having a two-stage control or throttle, and an elongate J-shaped yoke attached thereto and adapted lto receive a cooperating pair of male and female punching dies. The male die assembly has an elongate pilot pin which `is inserted .in a pre-formed pilot or bolt hole in the part and which insures that the punched holes will be located with respect to the bolt hole with positive dimensional accuracy. The tool is light,l compact, and easily handled by both male and female operators, and obviates the diiculties heretofore enumerated.

In operation, the punching tool is disposed substantially perpendicularly to the plane of 'the sheet in which the holes are to be punched, and the throttle of lthe pneumatic hammer is depressed to its first stage, enabling the operator to slowly 'and controllably advance the pilot pin into V,the pre-drilled or pre-punched bolt hole. After the pilot pin is inserted, the throttle or control is depressed to the -second stage', causing the hammer to rattle, and forcing the male punching dies through the sheet to lbe pierced. The resulting holes are, of course, perfectly aligned with the pilot or bolt hole and subsequent assembly of the component is easily and readily accomplished.

One of the more important features of this invention is the use, in the combination, of the vibratory or rattle type pneumatic hammer for the punching operation. This type of hammer renders a series of rapid, moderately heavy, blows instead ofthe one extremely heavy squeeze utilized by the stand-ard bench-type hammers. The use of the vibratory action instead .of the conventional squeeze o'bviates the necessity for a heavy, cumbersome ram required by a squeezen and makes for a heretofore unachieved lightness and compactness. In addition, the series of moderate blows results in dimensionally accurate, crack-free holes, whereas the previously used benchtype, single-stroke sqeezers frequently resultetl in skin crack around the edges of the holes, a condition that cannot be tolerated, particularly in aircraft Work. The absence of peripheral .cracks -is attributable to the fact that each moderately heavy blow, while sutliciently .forceful to enable a series of them .to accomplish piercing, is not so powerful as to cause bending, and subsequent cracking, at the hole .periphery at thefoutset of the operation, as is the case in the"squeeze technique. The ultimate strength of the metal is exceeded only in l`the hole area Aand not in the parent sheet itself. With the ever-increasing use of such 'relatively brittle materials as titanium, the ability to produce crack-'free holes simply and easily is extremely important. I

The presentlypreferred form `of this linvention fis illustratedin the accompanying drawings in which: y Y

Figure l is 4a side elevational view of Athe t'ool with the components shown in section y Figure 2 is a plan view of the tool with the valve fmechanism shown in section;

Figure 3 is an elarged fragmentaryview 'of lthe male `and female punch dies in position to punch the sheets,

with the assemblies shown in section. A v

As illustrated in Figure 1, the tool, such as the Ingersoll- Rand VVmodel AR-12 'as shown lin Ingersbll .Rand

k'catalog '5)60'6, 4th edition, 1949, comprises a {stand-ard, vibratory or rattle type of pneumatic hammer 12, having a body member 13, the body Amember having a mounting lug 14 adapted to receive a yoke or frame member on the lower portion thereof. Within the 'body memberfl 1of the 4hammer is located a rs't piston assembly ..115 :comprising a head block 17 adapted to slide or reciprocate within the body member, a hollow, elongate, spring biased barrel or piston 18 threadedly engagedwith head lblock v1'7, yand having within its bore 19 a second `piston or slugf 20 adapted to be rapidly reciprocated inthe bore by 'the air stream, and a spring-biased force transmitting member 22 disposed in the -end of the barrel 18 in axial alignment with piston 20 and adapted to receive and transmit the lpeicl'lssive forces of piston 20. In the uppermost end of body member 13 is a plunger member 23 slid-ably disposed in the ybody member and adapted to engage head fblock 17 in face-wise contact. Suitable Vvalve means 2.4 Vfor metering the incoming air to both the rear face of .plunger member 23 and t-o the second piston or slug 20, and controlled by control handle 25, permits the operator in 'a Well known manner to actuate either th first "piston .assembly 15 or the second piston 20, at his discretion. A

Attached to body member 13 at mounting lug 14 is an elongate, substantially J-shaped, frame or yoke lneirbci 26, 'having 'semi-permanently aixed female punching die assembly 27 at the lower end thereof. In this embodiment of the invention, the female punching die assembly 27 comprises two cylindrical sleeves 28 having hrdeied'pe. ripheral 'bosses 29 thereon, each of the sleeves 28 b'eiiig adapted to receive in sliding contact-a male punching die. Located between the holes 28 is an elongate, cylindrical pilot hole 30 which is adapted to slidably engage with a pilot pin in a male die assembly and guide 'the 'pilt pin and die assembly in its proper path. Fa-stened to yoke member 26 at about its inidpiit, is av die assembly receiving member 32havig substantially Ueshaped slot or cutin one end adaptedA to vpid guide a reciprocatable male punching die assembly $3 therein, and having a detachable cover plate 34cl'osii'igthe open end of the U to retain the die assembly in position. Slightly to the right (as shown in Figure l) of the llvshaped cut is located a Icylindrical spring retaining' 'or well 3s, having a coil spring 37 therein, the spring beingadapted to engage with a spring receiving stud 38 located on 'the male die assembly so as to urge the assembly :to its uppermost position at all times,

The male punching die a'ssembly 33 is slidably dis-N posed in receiving member 32 and its upper face 39 engages force transmitting member 22 in facewise contact at all times. It comprises "a solid, rectangular die holding block 40, having two standard male punching dies 41 disposed against stop shoulders 42 in die wells 43, each of the dies being locked in position by a spring loaded ball 44 which enters the block through channel 45 and engages with an annular groove 47 located in the mid-portion of the dies. To remove the dies, it is only necessary to unload the ball-biasing spring 48 slightly, permitting ball 44 to withdraw slightly upward in channel 45, and the dies 41 will drop out of the assembly.

New dies are'inserted by pushing them into thedie wells l 43 until they bottom on stop shoulder 42, then replacing spring 48 and ball 44 in the locking position. A round, elongate pilot pin 49 having a frusto-conical point 50 thereon is locatedin well 52 and is biased by spring 53, backed upl by threaded plug 55. The pilot pin 49 is substantially longer than vthe punching dies 41, and point 50 always protrudes through the rubber stripper block 54 which encases the lower ends of the male dies, thus permitting the tool operator to readily insert the pilot pin in the preformed hole. While normal practice is to use a pilot pinwhich )is about equal in diameter to the nut plate bolt hole, the pilot pin then penetrating fully throughthe preformed bolt hole in the sheet and engaging with the pilot hole in the female die assembly, in some in stances, however, it is not necessary to do this. If a bolt hole is smaller than the pilot pin, the operator need only insert the frusta-conical tip 50 of the pilot pin in the smaller hole where it will come to rest and act as a centering member for the punches, the resilient mounting 53 of the pin permitting it to retract into the die block with out damage.

In operation, the device is placed so that its longitudinal axis is substantially perpendicular to the plane of the sheet in which the holes are to be pierced. The operator depresses control handle 25 to its first stage or detent, causing valve 24 to admit metered air to the back (or .upper as shown) side of plunger member 23, said plunger `member 23 in turn forcing the entire first piston assembly slowly and controllably downward, permitting the operator to insert pilot pin 49 in the preformed hole in theV sheet. After the operator has inserted the pilot pin 49 in the hole so that stripper block 54 is snugly against the top of the sheet and the bosses 29 of female die 27 are rmly engaged against the lower side of the sheet, he depresses control handle 25 to the second stage, causing the valve V24 to direct additional air to actuate second piston or slug v while retaining the rst piston assembly 15 in its' lowered position. Slug 20 reciprocates rapidly, and hammers force transmitting member 22 which,

beinginfacewise contact with male die assembly 33, causes the dies 41 inthe assembly to apply a rapid series of punching forces to vthe sheets and ultimately force their way therethrough. The pilot pin 49, being in position in the pre-formed hole at all times during the piercing operation, insures that perfect alignment of the rivet holes and bolt hole is achieved.

.After piercing is accomplished, the first piston assembly 15 "iswithdrawn upwardly away from the sheet, permitting the male die assembly 33,to be also urged upwardly by theaction of spring 37 against stud 38, thereby with- :drawing the punching dies 41 from the completed holes and returning the unit to its Voriginal position. f f Different hole sizes are easily accommodated by simply removing cover plate 34 and the die assembly 33, and replacing the die assembly with one having the desired size punching zdies. The pilot pin may also vbe readily interchang'ed in this. manner. Worn or damaged pilot pins may mbe replaced by removing pilot pin s pring 53 and withdrawing the pilot pin from pilot pin well 52, and inserting a new pin.

While the disclosed embodiment shows the male punching dies and the pilot pin to be parallel and also coplanar, it is obvious that, without departing from the spirit of the invention, the spacial relationship between the dies and the pilot pin can be otherwise arranged. For example, for use in punching holes for so-called corner anchor nuts or nut plates, the dies and the pilot pin would be parallel, but disposed spacially at the vertices of a triangle. For onelug anchor nuts or nut plates, only one die need be used, or two dies both on the same side of the pilot pin.

While the presently preferred form of the invention has been illustrated and described herein, it will be appreciated that various changes may be made in the construction and arrangementl ofthe parts without departing from the spirit of the invention, and it is intended that all such changes shall be embraced within the scope of the following claims.

Iclaim:

1'. A portable punching tool comprising: a pneumatic hammer, 'said hammer comprising lirst piston means adapted to controllably advance a rcciprocatable punching die means, second piston means loca-ted within said first 'piston means, said second pist-on means being adapted to deliver 'rapid percussions, la force transmitting member disposed in`one end of said first piston means so as to receive the rapid percussions of said second piston means and. transmit them'to the reciproeatable punching die means, and control means arranged to provide independent control of the first and second piston means; frame' means attached to said pneumatic hammer for supportinga reciprocatable die means; male punching die means, including a pilot pin, disposed in said frame means and arranged to be controllably advanced by said first piston means to a preselected position whereat the pilot pin will pass through a preformed opening in a workpiece and to receive intermittent blows from said second piston 'moans when the preselected position is attained to punch thefworkpiece at points about the preformed opening; and female punching die means located in said frame means and disposed in coacting alignment with said male punching die means.

2. A portable punching tool, comprising: a yoke having oppositeends and an intermediate bight; a pneumatic hammer mounted on one of said ends and including a piston movable toward the other of said ends; an impact member on the piston selectively actuatable after said piston has moved toward said other end, the impact member being adapted to impart repeated blows to a punch; a female die on the other of the yoke ends and having a pilot hole therein; a member attached to and extending from 'the bight of the yoke and having a channel-like guideway 'for'supporting a die block therein; a die block mounted in the'guideway for reciprocation toward and away from 'said female die, said block having a guide pin and a male punch mounted therein, each said punch and pin having `an endl thereof projecting out of said block for respective cooperation with the pilot hole and female die the move- -ment of the piston effecting motion of the guide pin through a preformed opening in a workpiece and the subsequent actuation of the impact member causing the male punch to form an opening in the workpiece proximate the Apreformed opening; ya compressible stripper surrounding said projecting ends; resilient means normally urging said -block away from the female die; and a removable cover platemaintaining the block within the guideway whereby. :upon removal of the plate, the block may be moved laterally ofthe yoke ends for quick lassembly and disassembly.

f .3. In a portable punching tool, a sequential two-stage controllable pneumatic hammer including an impact member; a yoke member having two ends and an intermediate portion, said hammer being affixed to one of said ends; a female die having a pilot pin hole therein and being mollnietlvon the other of said yoke ends; a bracket with a slideway therein extending from the intermediate portion of the yoke with the slideway in alignment with the impact member and female die; a male punch assembly mounted for reciprooation in said slideway, said assembly including a slide block with bores therein; a punch in one of said bores adapted to cooperate with the female die; a pilot pin resiliently mounted in another of said bores, said pin being receivable through a preformed opening in material being punched into the pilot pin hole in the female die; resilient stripper means surrounding the punch and pilot pin; Asaid hammer in its rst stage being adapted to advance the punch assembly toward the female die to grip material being punched between the stripper means and female die and to advance the pilot pin into the preformed opening, and in its second stage to impart an impact to the punch to form an opening in the material gripped, the resilient mounting of said pilot pin allowing the pin to be forced back into the block in the event of misalignment with the aforesaid preformed opening.

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES Ingersoll-Rand Catalog 5606, 4th edition, 1949, showing model AR12 air-buck riveter. 

